.\"	$OpenBSD: DSA_dup_DH.3,v 1.7 2018/03/21 21:18:08 schwarze Exp $
.\"	OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
.\"
.\" This file was written by Ulf Moeller <ulf@openssl.org>.
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.Dd $Mdocdate: March 21 2018 $
.Dt DSA_DUP_DH 3
.Os
.Sh NAME
.Nm DSA_dup_DH
.Nd create a DH structure out of DSA structure
.Sh SYNOPSIS
.In openssl/dsa.h
.Ft DH *
.Fo DSA_dup_DH
.Fa "const DSA *r"
.Fc
.Sh DESCRIPTION
.Fn DSA_dup_DH
duplicates
.Vt DSA
parameters/keys as
.Vt DH
parameters/keys.
.Fa r->q
is lost during that conversion, but the resulting
.Vt DH
parameters contain its length.
.Sh RETURN VALUES
.Fn DSA_dup_DH
returns the new
.Vt DH
structure or
.Dv NULL
on error.
The error codes can be obtained by
.Xr ERR_get_error 3 .
.Sh SEE ALSO
.Xr DH_new 3 ,
.Xr DSA_get0_pqg 3 ,
.Xr DSA_new 3 ,
.Xr ERR_get_error 3
.Sh HISTORY
.Fn DSA_dup_DH
first appeared in OpenSSL 0.9.4 and has been available since
.Ox 2.6 .
.Sh CAVEATS
Be careful to avoid small subgroup attacks when using this.
